Nanosecond pulsed power sources having multi-core transformers

ABSTRACT

Described herein are apparatuses and methods for applying high voltage, sub-microsecond (e.g., nanosecond range) pulsed output to a biological material, e.g., tissues, cells, etc., using a high voltage (e.g., MOSFET) gate driver circuit having a high voltage isolation and a low inductance. In particular, described herein are multi-core pulse transformers comprising independent transformer cores arranged in parallel on opposite sides of a substrate. The transformer cores may have coaxial primary and secondary windings. Also describe are pulse generators including multi-core pulse transformers arranged in parallel (e.g., on opposite sides of a PCB) to reduce MOSFET driver gate inductance.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/881,589, filed Aug. 4, 2022, titled “NANOSECOND PULSED POWER SOURCESHAVING MULTI-CORE TRANSFORMERS,” published as U.S. Patent ApplicationPublication No. US 2022/0370801, which is a continuation of U.S. patentapplication Ser. No. 16/719,920, filed Dec. 18, 2019, titled “NANOSECONDPULSED POWER SOURCES HAVING MULTI CORE TRANSFORMERS,” now U.S. Pat. No.11,452,870, each of which are herein incorporated by reference in theirentirety.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by reference.

FIELD

Described herein are pulsed power sources that include parallel,multi-core pulse transformers for MOSFET gate drivers. These apparatuses(systems and devices) generally relate to high voltage, sub-microsecond(e.g., nanosecond, picosecond, etc.) pulsing. In particular, describedherein are nanosecond pulsing systems and apparatuses capable ofdelivering a high voltage, nanosecond pulsed electrical fields (nsPEF)for electrotherapy using parallel, multi-core (e.g., two or more core)pulse transformers.

BACKGROUND

A “nanosecond pulsed electric field” (nsPEF) may be applied for medicaland/or therapeutic purposes, including in particular for the treatmentof biological materials (e.g., cells and tissues). NsPEF may include anelectrical field with a pulse width that may be less than about 1000nanosecond (ns), such as between about 0.1 ns and 1000 ns, and may havepeak voltages that are high voltage, in some variations as high as about1 kV/cm, 2 kV/cm, 3 kV/cm, 4 kV/cm, 5 kV/cm, about 10 kV/cm, about 20kV/cm, about 50 kV/cm, about 100 kV/cm, about 250 kV/cm, or about 500kV/cm. Such high voltage, very brief pulses present unique problems fortherapeutic medical devices. In particular, the delivery of rapidlychanging (e.g., nanosecond or faster pulses) at high voltage may requirevery rapid MOSFET response times, requiring low MOSFET gate drivercircuit inductance.

Therefore, it is desirable to provide devices and apparatuses, includingsystems for nanosecond pulsed electrical field generation and deliverythat are configured to provide sub-microsecond (e.g., nanosecond)pulses, including pulses of 100 ns or less, that have fast output pulserise times and falling times, that may also be pulsed with short delaytimes. Such apparatuses and methods will be particularly useful in thegrowing field of therapeutic nsPEF, including for medical treatments,including treatments of cancer/tumors, skin disorders and otherapplications.

SUMMARY OF THE DISCLOSURE

Described herein are apparatuses (systems, devices, etc.), and methodsconfigured to apply high voltage, sub-microsecond (e.g., nanosecondrange) pulsed output to a biological material, e.g., tissues, cells,etc., with very fast output pulse rise time and fall times.

Some of the apparatuses and methods described herein may be configuredfor delivering nanosecond pulsed electrical energy and may include, forexample, one or more MOSFET drivers, one or more MOSFETs, and aplurality of parallel pulse transformers each comprising an independenttransformer core wherein a plurality of primary and secondary windingsare wrapped around each core. The primary and secondary windings may becoaxial relative to each other. Each of the one or more MOSFET driversmay be connected in parallel to the primary windings, and wherein eachof the one or more MOSFETs are connected in parallel to the secondarywindings.

For example, described herein are apparatuses for deliveringsub-microsecond pulsed electrical energy that include two or more (e.g.,dual-core, multi-core, etc.) pulse transformers having a high voltageisolation and a low circuit inductance, coupling one or more highvoltage switches drivers (e.g., MOSFET drivers) to one or more highvoltage switches (e.g., MOSFETs). In particular, described herein aresub-microsecond pulse generators that include HV switch driver circuitsincluding one or more (and particularly two) pulse transformers asdescribed herein, in which the two (or more) cores are independent ofeach other and are each wound with two or more cables forming theprimary and secondary windings that may be arranged in parallel, withthe primary connected to the HV switch driver(s) and the secondaryconnected to the HV switch/gate(s). The pulse transformers may bearranged in parallel; in some advantageous variations on opposite sidesof the substrate holding the HV switch circuitry.

The sub-microsecond (e.g., nanosecond) pulse generator may be, forexample, a tunable, high-voltage, sub-microsecond pulse generator basedon a Marx-Switch stack hybrid circuit, having a plurality of differentstages that each include, at each stage, a stack of power HV switchesthat allow relatively high charging voltages at each stage, permittingan overall output voltage with a single trigger. For example, see U.S.application Ser. No. 15/148,334 (publication no. US20170245928A1, titled“High-voltage analog circuit pulser with feedback control”), hereinincorporated by reference in its entirety.

For example, the sub-microsecond pulse generator may be configured toprovide at least a 200 kV/μs high voltage, high-current pulsed output.The high voltage (in some variations, high current) pulsed outputgenerated by the sub-microsecond pulse generator may be, for example,configured to have a voltage of greater than 15 kV and an output currentof greater than 300 A.

The apparatuses described herein may be configured to operate with apulse delivery output that is configured to deliver the high voltage,high current, nanosecond pulses to a biological tissue. For example, thepulse delivery output may comprise a handpiece configured to deliver thehigh voltage pulsed output. In some variations, the handpiece mayinclude a removable tip having a plurality of tissue-penetratingelectrodes. For example, any of the handpieces as described in U.S.patent application Ser. No. 16/247,469 (“TREATMENT TIP WITH PROTECTEDELECTRODES”), filed on Jan. 14, 2019, and incorporated by reference inits entirety herein, illustrate examples of handpieces having removabletips that may be used. A handpiece may be used to deliver therapeuticenergy to treat a tissue (e.g., skin, tumor, etc.) in a living subject(e.g., in vivo) or in tissue removed from a subject (e.g., ex vivo).

In some variations the apparatus may include a pulse delivery outputthat is configured as a cuvette (e.g., a cuvette fixture) or chamber fordelivering high voltage nanosecond pulses. These apparatuses may be usedwith isolated portions of biological material, including extractedand/or cultured cells. For example, these apparatuses and methods may beused for electroporation.

Also described herein are methods of using any of the apparatusesdescribed herein to apply high voltage nanosecond pulsing from a pulsegenerator. These methods may be methods for delivering the high voltage(in some cases high current) nanosecond pulses to a patient. Forexample, any of the apparatuses described herein may be used as part ofa method of delivering nanosecond pulsed electrical energy to abiological material (such as a patient's tissue). In some variations,the method may alternatively include delivering the pulse output from apulse delivery output that includes a cuvette chamber, e.g., toelectroporate isolated tissue and/or cells.

The high voltage, high current, pulsed output may have, e.g., a voltageof at least 200 kV/μs.

For example, described herein are apparatuses for deliveringsub-microsecond pulsed electrical energy including a pulse transformer.These apparatuses may include: one or more high voltage switch drivers;one or more high voltage switches; and one or more multi-core pulsetransformers, wherein each multi-core pulse transformer comprises afirst transformer core and a second (or more) transformer core that arearranged in parallel between the one or more high voltage switchesdrivers and the one or more high voltage switches, wherein the firsttransformer core and the additional transformer core(s) each include oneor more cables (in some variation, coaxial cables) forming primary andsecondary windings; further wherein the one or more high voltage switchdrivers are coupled to the primary windings and the one or more highvoltage switches are coupled to the secondary windings.

In any of these apparatuses, the first transformer and the second (ormore) transformer may be symmetrically arranged in parallel between theone or more high voltage switches drivers and the one or more highvoltage switches.

In general, the one or more high voltage switches may be MOSFETs and theone or more high voltage switch drivers may be MOSFET drivers. Othertransistors (e.g., field-effect transistors) may be used.

For example, described herein are apparatuses (e.g., including a pulsetransformer) for delivering sub-microsecond pulsed electrical energycomprising: one or more MOSFET drivers on a substrate; one or moreMOSFETs on the substrate; and a parallel multi-core pulse transformercomprising a first transformer core and a second, independent,transformer core, wherein a plurality of coaxially arranged primary andsecondary windings are wrapped around each of the first and secondtransformer cores, wherein the first transformer core is on a first sideof the substrate and the second transformer core is on an opposite sideof the substrate; further wherein each of the one or more MOSFET driversis connected in parallel to the primary windings, and wherein each ofthe one or more MOSFETs are connected in parallel to the secondarywindings.

In any of these apparatuses, the primary and secondary windings may becoaxially arranged relative to each other.

The one or more MOSFET drivers may be coupled to the primary windings sothat each primary winding is electrically parallel, and wherein the oneor more MOSFETs are coupled to the secondary windings so that eachsecondary winding is electrically parallel.

In general, the apparatus first core may be independent from the secondcore (e.g., electrically independent). In some variations the first coreis separated from the second core by the substrate (e.g., the printedcircuit board, PCB). In general, the first core may be arrangedsymmetrically between the high voltage gate/switch (e.g., MOSFET) andthe high voltage gate/switch (e.g., MOSFET) driver. For example, thefirst core may be arranged on a first side of a printed circuit board(PCB) to which the one or more MOSFET drivers and one or more MOSFETsare attached, and the second core may be arranged on a second side ofthe PCB opposite from the first side.

In some variations for each transformer core, the plurality of coaxialcables are wound between 1 and 5 times around.

Any number of high voltage date/switches (e.g., MOSFETS) may be used.For example, the one or more MOSFETs may comprise a plurality ofMOSFETs; the one or more MOSFET drivers comprises a plurality of MOSFETdrivers.

Also described herein are pulse generators using any of these pulsetransformers. For example, a sub-microsecond pulse generator comprisinga pulse transformer as described above may be configured to provide atleast a 200 kV/μs high voltage pulsed output. The pulse generator mayinclude a handpiece configured to deliver the high voltage pulsedoutput. The handpiece may include a removable tip having a plurality oftissue-penetrating electrodes. The high voltage pulsed output generatedby the sub-microsecond pulse generator may be configured to have avoltage of 1 kV or greater (e.g., in some variations, preferably 5 kV orgreater, preferably 10 kV or greater, preferably 15 kV or greater, etc.)and an output current of 20 A or greater (e.g. preferably 50 A orgreater, preferably 100 A or greater, preferably 200 A or greater, morepreferably 300 A or greater, etc.).

For example, described herein are apparatuses for deliveringsub-microsecond pulsed electrical energy that may include: one or moreMOSFET drivers; one or more MOSFETs; and one or more multi-core pulsetransformers, e.g., a dual-core pulse transformer, wherein eachdual-core pulse transformer comprises a first transformer core and asecond transformer core that are arranged in parallel between the one ormore MOSFET drivers and the one or more MOSFETs so that the firsttransformer core is on a first side of a substrate and the secondtransformer core is on a second side of the substrate in parallel withthe first transformer core; further wherein the one or more MOSFETdrivers are coupled to a primary winding from each of the first andsecond transformer core, and the one or more MOSFETs are coupled to asecondary winding from each of the first and second transformer core.The one or more MOSFET drivers may be coupled to the primary windings sothat each primary winding is electrically parallel, and wherein the oneor more MOSFETs are coupled to the secondary windings so that eachsecondary winding is electrically parallel.

Although many of the examples described herein are dual-core pulsetransformers having a first core and a second core that are independentand arranged in parallel, it should be understood that more than twocores may be used and arranged as described herein. Thus, the methodsand apparatuses for reducing inductance (and increasing MOSFET drivecurrent due to keeping each core below saturation) by paralleling twoindependent cores (e.g., dual-cores) can be extended to more than twocores.

Further, although the examples described herein include primary andsecondary windings that are coaxially related to each other, this is notnecessary. Coaxially arranged primary and secondary windings may furtherlower leakage inductance and therefore enhance the current transferacross the transformers described herein. For example, in somevariations, the secondary windings may be coaxially arranged over theprimary windings (or vice versa). The one or more MOSFETs may comprisesa plurality of MOSFETs, and/or the one or more MOSFET drivers maycomprise a plurality of MOSFET drivers. As mentioned above, asub-microsecond pulse generator may include a pulse transformers whereinhigh voltage pulsed output generated by the sub-microsecond pulsegenerator is configured to have a voltage of greater than 5 kV and anoutput current of greater than 200 A.

Also described herein are methods of generating a sub-microsecond pulsedoutput, the method comprising: emitting a driving pulse from a highvoltage switch driver to a multi-core pulse transformer through aprimary winding of a first transformer core and a primary winding of asecond transformer core, wherein the first and second transformer coresare arranged in parallel (e.g., in some variations on either sides of asubstrate); and receiving the driving pulse at a high voltage switchfrom a secondary winding (for example, coaxially arranged relative theprimary winding around the first transformer core and the secondtransformer core); wherein the driving pulse is a sub-microseconddriving pulse.

The high voltage switch may be a MOSFET and the high voltage switchdriver may be a MOSFET driver. The MOSFET, MOSFET driver and firsttransformer core may be on a first side of a substrate (e.g., PCB), andthe second transformer core may be on a second side of the substratedirectly opposite from the first transformer core. The driving pulse maybe emitted through a plurality of primary windings that are arranged inparallel. The primary windings and the secondary windings may be formedby a plurality of lengths of coaxial cable wrapped around the firsttransformer core and the second transformer core. Each of the firsttransformer core and the second transformer core may be wrapped by aplurality of lengths of coaxial cable.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 is a schematic of one example of a portion of a pulse generatorincluding a pair of parallel pulse transformers as described herein.

FIG. 2A is one example of a pulse transformer using a coaxial cable asprimary and secondary as described herein.

FIG. 2B is an example of a pulse transformer using two coaxial cables inparallel as the primary and secondary windings as described herein.

FIG. 3 is an example of two pulse transformers arranged in parallel eachhaving an independent core wound with a plurality of cables connected inparallel between the MOSFET driver chip and the MOSFET (e.g., as part ofthe MOSFET gate driver). This configuration may be referred tocollectively as a multi-core (e.g., dual-core) pulse transformer.

FIG. 4 is an example of a multi-core pulse transformer including twoindependent transformer cores that each have a plurality of coaxialcables (two are shown) forming primary and secondary windings in whichthe primaries are all electrically parallel and connected to a pluralityof MOSFET drivers while the plurality of secondaries are allelectrically parallel and connected to a plurality of MOSFETs.

FIG. 5 is one example of an apparatus for delivering high voltage, shortpulses of electrical energy, such as nanosecond pulsed electrical energyincluding a pulse transformer as described herein.

DETAILED DESCRIPTION

In general, the methods and apparatuses (e.g., devices, systems, etc.)described herein for pulsed power systems parallel, multi-core pulsetransformers for high voltage (HV) switch drivers that are configured toprovide very rapid on/off switching of the HV switch driver circuit(s)while preserving sharp rise time and fall times, e.g., when pulsing atsub-microsecond (e.g., nanosecond, including 1000 ns or less, 100 ns orless, etc.) output pulsing. In general, the HV switches described hereinmay be any high voltage switch/gate, such as transistors (e.g.,field-effect transistors), including MOSFETs (driven by MOSFET gatedriver circuits). These high voltage switches may be referred to hereinfor convenience as MOSFETs.

These methods and apparatuses may include small core/transformersarranged in multi-core configurations in which the pulse transformersare compact and configured in parallel to lower HV switch driver circuitinductance. This will allow the HV switch/gate(s), for example, theMOSFET(s) to be turned on/off fast (e.g., in the nanosecond range orless), and will also allow the HV switch turn on and turn off delay timeto be correspondingly fast and may further provide faster load arcingprotection.

Although the methods and apparatuses are described in the context of asub-microsecond pulse generator for applying high voltage,sub-microsecond (e.g., nanosecond range) pulsed output to a biologicalmaterial, e.g., tissues, cells, etc., these methods and apparatuses(including in particular the pulse transformer configurations describedherein, may be used with or as part of any HV switch driver circuit thatuses a pulse transformer.

Further, the transformers (cores) described herein may be configured aslow-power pulse transformers that typically reduce the inductance of thecoupling from the HV switch (e.g., MOSFET) driver circuit to the HVswitch (e.g., MOSFET transistor or power switch), as illustrated in theschematic of FIG. 1 . In FIG. 1 , the pulse transformer portion of apulse generator is shown schematically, illustrating the driver (HVswitch driver, shown in this example as a MOSFET driver 101) connectedvia the primary windings to a pair of parallel transformers 103, 103′that is in turn connected via the secondary windings to the HVswitch/gate(s) (shown in this example as MOSFETs 105).

The transformers may include a single core with multiple parallelwindings on the same core, or more preferably multiple cores that arearranged in parallel and/or symmetrically between the HV switch/gate(s)and HV switch driver(s). The multiple parallel windings may be madeusing a coaxial arrangement of the primary and secondary windings. Thus,the primary and secondary winding may be formed of a coaxially arrangedcable in which, e.g., the primary windings are coaxially arranged overthe secondary winding (alternatively, in some variations the secondarywinding may be coaxially arranged over the primary winding). A singlecore with multiple parallel windings on the same core will saturate thecore, as the saturation depends on the total coupled flux of thewindings to the core.

FIG. 2A schematically illustrates one example of a transformer in whicha transformer core 202 is wrapped by a coaxial cable 204 in which theprimary winding 107, 107′ is coaxially arranged around the secondarywinding 109, 109′. The coaxial arrangement shown in FIG. 2 is a singlecore with a single winding on the core. The use of coaxial cable for theprimary and secondary windings may lower the leakage inductance. In somevariations, two or more turns of the transformer primary and secondarycan be used. In FIG. 2A, a single turn of the coaxially arranged primaryand secondary windings is shown. In some variations more than one (e.g.,2, 3, 4, 5, between 1 and 10, between 1 and 7, between 1 and 5, lessthan 5, etc., including half turns such as 1.5, 2.5, 3.5, etc.) may beused. Alternatively or in addition, in some variations a single core maybe wrapped with multiple coaxial cables arranged in parallel, as shownin FIG. 2B.

In FIG. 2B, the pulse transformer may include two coaxial cables 214,214′ arranged in parallel on the transformer core 202. Each coaxialcable is shown with a single turn in this example. In some variationsmore than 1 turn (e.g., 1.5, 2, 2.5, 3, 3.5, etc.) may be used, asmentioned above. Alternatively or additionally, additional length ofcoaxial cable may be arranged in parallel around the core, for a totalof 2, 3, 4, 5, 6, etc. lengths or coaxial cables in which the primarywindings 107, 107′ are arranged in parallel with each other (e.g., eachreceiving the primary input, and the primary output) and coaxiallyaround secondary windings 109, 109′; each secondary winding is arrangedin parallel (e.g., receiving the same secondary input and the samesecondary output). The variation shown in FIG. 2B may result insubstantially lower inductance, e.g., by including two or more coaxialcables for the parallel primary and secondary windings on eachtransformer of a pulse transformer.

In some variations the core saturation may be improved by addingmultiple cores in parallel, rather than multiple windings per core.Thus, the incorporation of independent (not magnetically coupled) coreswith parallel windings may allow a higher drive current withoutsaturating the cores and, by having more than one circuit in parallel,may reduce the inductance between the driver and the HV switch (e.g.,MOSFET), or driven switching element. For example, FIGS. 3 and 4 showmultiple, independent cores arranged in parallel.

The pulse transformers described herein may be used as part of (or inconjunction with) a HV switch driver circuit for high voltage isolation,as will be described in greater detail below. Any of the pulsetransformers 300 described herein may be configured as a multi-corepulse transformer that includes a first and second transformer corearranged in parallel, as shown in FIG. 3 . In FIG. 3 two transformercores 302, 302′ of the pulse transformer 300 are shown. The twotransformer cores may be placed on opposite sides (e.g., top and bottomsides) of a substrate 319, e.g., printed circuit board (PCB), on whichthe pulse generator circuitry, including the HV switch driver chip(s)311 and HV switch/gate(s) 309 are arranged. The two cores shown in FIG.3 (comprising two pulse transformers) are arranged in parallel, whichmay reduce the HV switch driver circuitry inductance.

In FIG. 3 , the HV switch driver chip 311 is coupled to the primarywinding of a pair of pulse transformers each including a transformercore 302, 302′ and two (or in some cases more) coaxial cables configuredas the primary and secondary windings. The coaxial cables forming theprimary and secondary windings are arranged in parallel for each of thecores. A first pulse transformer is positioned on the first side of thesubstrate (e.g., the top of PCB 319) and includes a single core 302 anda pair of coaxial cables 314, 314′ forming the primary and secondarywindings that are electrically parallel. A second pulse transformer ispositioned on the second side of the substrate (e.g., the bottom of PCB319) and also includes a single core 302′ and a pair of coaxial cables316, 316′ forming the primary and secondary windings that areelectrically parallel with each other and with the primary and secondarywindings in the first pulse transformer. The primary windings areconnected to the HV switch driver chip 311 and the secondary windingsare connected to the HV switch 309. Thus, FIG. 3 shows a dual-core pulsetransformer including two independent cores 302, 302′ arranged inparallel for a HV switch driver.

In some variations, multiple HV switch drivers (e.g., HV switch drivercircuitry such as MOSFET driver chips) and/or multiple HV switches maybe included and coupled to pulse transformers as shown. For example,FIG. 4 shows one variation in which two or more MOSFET driver chips 311,311′ are arranged in parallel and electrically connected via a dual-corepulse transformer having two independent cores 302, 302′ arranged inparallel to two or more MOSFETs 309, 309′. In FIG. 4 , all of theprimary windings are arranged in parallel and electrically coupled tothe outer coaxial conductor while the secondary windings are also allarranged in parallel and electrically coupled to the inner coaxialconductor; thus, the primary is arranged coaxially around the secondarywinding.

The pulse transformers described herein may allow the use of smaller,multiple, pulse transformer cores that may provide a more compactimplementation compared to cores with similar saturation that mayotherwise need to be larger and more bulky, typically having a higherinductance. As shown in FIG. 4 , at least two cores, arranged inparallel and independently, may be used. In some variations, more thantwo cores may be used and arranged in parallel, which may further avoidcore saturation while decreasing the inductance of the coupling from thedriver to the power HV switch (switching device, e.g., MOSFET).

Any of the pulse transformers described herein may be particularly wellsuited for use as part of a pulse generator for treating a biologicalmaterial (e.g., cells, tissue, etc.). For example, FIG. 5 illustratesone example of an apparatus for delivering sub-microsecond (e.g.,nanosecond) pulsed electrical energy that includes a pulse generatorconfigured to provide a high voltage pulsed output in the nanosecondrange (e.g., less than 1000 ns). Examples of pulse generators that mayinclude the pulse transformer(s) described herein may include thosedescribed in U.S. patent application Ser. No. 15/148,344 (published asUS20170245928A1), filed on May 6, 2016, and U.S. Ser. No. 15/269,273(published as US20180078755A1), which was filed on Sep. 19, 2016, andU.S. Ser. No. 15/595,684 (now U.S. Pat. No. 10,252,050B2). Each of thesepatents and patent applications is herein incorporated by reference inits entirety herein.

In operation, a system including one or more pulse transformers mayapply high voltage, nanosecond-duration pulse waveforms. The pulsetransformer may further help reduce or eliminate arcing. FIG. 5illustrates one example of a therapeutic apparatus for deliveringnanosecond pulsed electrical energy that may include a pulse transformeras described herein. For example, described herein are apparatuses(e.g., nanosecond pulsed electrical fields (nsPEF) apparatuses) that mayinclude one or more pulse transformers that may lower HV switch (e.g.,MOSFET) driver circuit inductance. These apparatuses may be configuredto provide pulse widths from 50 ns to 1 μs, having rise and fall-times,for example, of about 20 ns or less, pulse voltages as high as 1-15 kV(e.g., 10-15 kV, in some variations 18 kV or more). In some variationsthe pulse currents may be up to about 500 A (or greater). Theseapparatuses may be referred to herein as pulse generators orsub-microsecond pulse generators and may be a modified Marx high voltagepulse generator. This circuit/system architecture may include aplurality of HV switches that may be closed to deliver the nanosecondpulses over a transmission cable, and the HV switches may include (or becoupled with) one or more pulse transformers, such as a multi-core pulsetransformer having at least two cores arranged in parallel. In anexemplary Marx high voltage pulse generator low-voltage pulse timing andtriggering circuits may share common circuitry with system low voltageDC supply and system input control signals. Any of these apparatuses mayinclude a multi-core (e.g., a dual-core) pulse transformer (having twoor more independent cores) sharing parallel and, for example, coaxialprimary and secondary windings connecting to one or more MOSFET drivers(e.g., MOSFET driver circuits or MOSFET driver chips) and one or moreMOSFET(s).

FIG. 5 illustrates one example of an apparatus (e.g., a system) 500 fordelivering high voltage, short pulses of electrical energy, such asnanosecond pulsed electrical energy, that includes a pulse generator 507which may also include a multi-core pulse transformer.

In FIG. 5 , the apparatus may include a pulse delivery output (e.g.,configured as a handpiece 502) and the pulse generator 507, with one ormore inputs (e.g., footswitch 503, and user interface 504). Footswitch503 is connected to housing 505 through connector 506; the housing mayenclose the electronic components, including the pulse generator 507including the dual-core pulse transformers with parallel coaxial primaryand secondary windings (not visible), and a fixed length of thetransmission cable (inside the dashed outline 522). The handpiece 502may include electrodes (e.g., a removable or swappable electrode tip521) and connects to the pulse generator 507 circuitry through thetransmission cable 516. The high voltage system 500 may also include astorage drawer 508, inputs (e.g., buttons, keyboard, etc.), and amonitor (user interface) 504. Additional circuitry (e.g., controlcircuitry, wireless circuitry, etc.) may be included as well. The systemmay also include a handle 510 and a faceplate 512.

A human operator may adjust one or more of the following settings of thesystem: the number of pulses, current or voltage amplitude, pulseduration, and pulse frequency, for example, by entering them into anumeric keypad or a touch screen of interface 504; alternatively oradditionally, the user may select from one or more predefined protocolsthat include predetermined parameter settings. In some embodiments, thepulse width can be varied (e.g., within a defined range, such as between1 ns and 1000 ns). A control unit or microcontroller (e.g., within thehousing, not shown) may send signals to pulse control elements withinthe system 500.

In some variations, the apparatuses and methods described herein may beused for electroporation of biological material in a container (e.g., ina cuvette). The chamber, or cuvette, may be any appropriate size. Forexample, the container may be small and may have an electrical pulseimpedance of ˜15Ω. The electroporation pulse width may be in thenanosecond range and the voltage used can be many kV, such as 5 kV to 8kV.

The apparatuses described herein may enable multi-kilovolt nanosecondpulses to be delivered to a cuvette.

As mentioned above, in many high voltage/high-power pulse generatordesigns the high voltage is rapidly switched from an energy storagecircuit into a pulse generation path. A typical high voltage/high-powerpulse generator example is the Marx generator, which is a designed tocharge high voltage capacitors in parallel and then rapidly switch thesecharged capacitors to a series circuit that discharges through adifferent circuit than the charging circuit by switching MOSFETs using agate driver. The apparatuses and methods described herein may helpensure high voltage isolation of the gate driver circuit and maintain alow circuit inductance. As described above, this may be accomplished byusing the pulse transformers, e.g., multi-core pulse transformersarranged in parallel (and having parallel coaxial primary and secondarywindings).

The pulse transformers described herein, and any pulse generatorsincluding them, may include the use of a primary and secondary winding,for example, coaxial as this configuration may be best for the parallel,dual-core pulse transformers described herein. The use of coaxialprimary and secondary windings may reduce the leakage inductance of thepulse transformer. The arrangement of the primary and secondary may beswitched (e.g., the primary may be coaxially arranged over the secondaryor the secondary may be coaxially arranged over the primary). Generally,the coaxial arrangement may minimize leakage inductance and optimizecoupling from primary to secondary. The coaxially cabling is generallyselected so that its primary to secondary insulation rating issufficiently high to prevent arcing or corona during operation of theapparatus, as the MOSFET (HV switch) banks (secondary) can be greaterthan about 5 kV (e.g., greater than about 1 kV, 5 kV, 10 kV, 12.5 kV, 15kV, etc.) relative to the drive circuit (primary). In some variations itmay be beneficial to minimize the length of the coaxial cabling, whichmay determine the coupling capacitance from primary to secondary.Typically the greater the length, the higher the primary to secondarycapacitance and this can result in HV pulse feedback into the drivercircuits, causing erratic pulsing and inducing MOSFET failures.

The use of multiple parallel transformers forming the (e.g., multi-core,such as dual-core) pulse transformers advantageously allow a lowerinductance from the drive circuitry to the driven high voltage (HV)switches (e.g., MOSTFETs), while increasing the switch drive currentwithout suturing the pulse transformer cores. More than two pulsetransformers may be arranged in parallel. A pulse generator (such as thepulse generator shown in FIG. 5 ) may include a plurality of drivers(e.g., MOSFET drivers) that are triggered by a trigger input. Pairs ofMOSFET drivers may be coupled to a bank of MOSFETs (e.g., 3, 4, 5, 6,etc. MOSFETS; more or fewer MOSFETS may be used) by a multi-core andparallel pulse transformer (“dual pulse transformer). Two drivers may becoupled to each MOSFET bank through each multi-core pulse transformer.The MOSFETs may be arranged in parallel for increased output current. Inthis example, the output of each the MOSFET bank may be coupled to aprotection circuit.

The dual-core pulse transformer in this example may be similar to thatshown in FIG. 4 , in which a pair of cores is arranged in parallel andsymmetrically about opposite sides of the printed circuit board.

The shape, size or type of the transformer core may be varied. In thevariations described herein, which may be configured to provide aparticularly compact pulse generator, the transformer cores may beconfigured to be sufficiently small so that they do not increase thespacing between the MOSFET (HV switch) banks, yet be sufficiently largesuch that they do not quickly saturate, reducing primary to secondarycoupling.

A prototype circuit for a pulse generator implementing the pulsetransformer may include a plurality of dual-core pulse transformers aspart of the pulse generator board, with one core of each dual-core pulsetransformer on the front side and the parallel core for each dual-corepulse transformer on the opposite side of the circuit substrate (e.g.,printed circuit board). This may allow the board to remain in contactwhile increasing the MOSFET drive capability due to the parallel pulsetransformers. The first side of the PCB (e.g., top side) may include anarray of MOSFET switches, arranged in three stages for each of sevenbanks, e.g., in some variations with four FETs per bank. The top-sidehalf of the dual-core pulse transformers may be positioned between theMOSFETS and the MOSFET drivers (two per MOSFET bank), as shown. Thebottom-side half of the dual-core pulse transformers may be oppositefrom a top-side half. The top-side half and bottom-side half may bearranged in parallel, on either side of the PCB, minimizing the distancethat the windings (coaxial cable forming the primary and secondarywindings) must traverse to connect between the MOSFET drivers andMOSFETs. In some variations, pairs of MOSFET drivers may connect to thetop-side core of a plurality of dual-core pulse transformers, which mayin turn coupled to the MOSFETs. The MOSFETs may be arranged as amulti-bank stack of MOSFET switches with multiple MOSFETs (e.g., 3, 4,5, 6, etc.) in parallel per bank. The MOSFETS may, in turn, be coupledto parallel protection circuits.

In operation, the dual-core pulse transformers described herein mayresult in a lower circuit inductance, increased speed for turning on/offthe MOSFETs (and/or reducing delay times) and faster load arcingprotection, due to the parallel configuration of the multiple cores, andin some variations the use of coaxial windings. This may result in alower driving point inductance (e.g., at the MOSFET driver outputs) andhigher drive current to the MOSFETs.

Any of the methods (including user interfaces) described herein may beimplemented as software, hardware or firmware, and may be described as anon-transitory computer-readable storage medium storing a set ofinstructions capable of being executed by a processor (e.g., computer,tablet, smartphone, etc.), that when executed by the processor causesthe processor to control perform any of the steps, including but notlimited to: displaying, communicating with the user, analyzing,modifying parameters (including timing, frequency, intensity, etc.),determining, alerting, or the like.

When a feature or element is herein referred to as being “on” anotherfeature or element, it can be directly on the other feature or elementor intervening features and/or elements may also be present. Incontrast, when a feature or element is referred to as being “directlyon” another feature or element, there are no intervening features orelements present. It will also be understood that, when a feature orelement is referred to as being “connected”, “attached” or “coupled” toanother feature or element, it can be directly connected, attached orcoupled to the other feature or element or intervening features orelements may be present. In contrast, when a feature or element isreferred to as being “directly connected”, “directly attached” or“directly coupled” to another feature or element, there are nointervening features or elements present. Although described or shownwith respect to one embodiment, the features and elements so describedor shown can apply to other embodiments. It will also be appreciated bythose of skill in the art that references to a structure or feature thatis disposed “adjacent” another feature may have portions that overlap orunderlie the adjacent feature.

Terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention.For example, as used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, steps, operations, elements, components, and/orgroups thereof. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items and may beabbreviated as “/”.

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if a device in thefigures is inverted, elements described as “under” or “beneath” otherelements or features would then be oriented “over” the other elements orfeatures. Thus, the exemplary term “under” can encompass both anorientation of over and under. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Similarly, the terms“upwardly”, “downwardly”, “vertical”, “horizontal” and the like are usedherein for the purpose of explanation only unless specifically indicatedotherwise.

Although the terms “first” and “second” may be used herein to describevarious features/elements (including steps), these features/elementsshould not be limited by these terms, unless the context indicatesotherwise. These terms may be used to distinguish one feature/elementfrom another feature/element. Thus, a first feature/element discussedbelow could be termed a second feature/element, and similarly, a secondfeature/element discussed below could be termed a first feature/elementwithout departing from the teachings of the present invention.

As used herein in the specification and claims, including as used in theexamples and unless otherwise expressly specified, all numbers may beread as if prefaced by the word “about” or “approximately,” even if theterm does not expressly appear. The phrase “about” or “approximately”may be used when describing magnitude and/or position to indicate thatthe value and/or position described is within a reasonable expectedrange of values and/or positions. For example, a numeric value may havea value that is +/−0.1% of the stated value (or range of values), +/−1%of the stated value (or range of values), +/−2% of the stated value (orrange of values), +/−5% of the stated value (or range of values), +/−10%of the stated value (or range of values), etc. Any numerical valuesgiven herein should also be understood to include about or approximatelythat value, unless the context indicates otherwise. For example, if thevalue “10” is disclosed, then “about 10” is also disclosed. Anynumerical range recited herein is intended to include all sub-rangessubsumed therein. It is also understood that when a value is disclosedthat “less than or equal to” the value, “greater than or equal to thevalue” and possible ranges between values are also disclosed, asappropriately understood by the skilled artisan. For example, if thevalue “X” is disclosed the “less than or equal to X” as well as “greaterthan or equal to X” (e.g., where X is a numerical value) is alsodisclosed. It is also understood that the throughout the application,data is provided in a number of different formats, and that this data,represents endpoints and starting points, and ranges for any combinationof the data points. For example, if a particular data point “10” and aparticular data point “15” are disclosed, it is understood that greaterthan, greater than or equal to, less than, less than or equal to, andequal to 10 and 15 are considered disclosed as well as between 10 and15. It is also understood that each unit between two particular unitsare also disclosed. For example, if 10 and 15 are disclosed, then 11,12, 13, and 14 are also disclosed.

Although various illustrative embodiments are described above, any of anumber of changes may be made to various embodiments without departingfrom the scope of the invention as described by the claims. For example,the order in which various described method steps are performed mayoften be changed in alternative embodiments, and in other alternativeembodiments one or more method steps may be skipped altogether. Optionalfeatures of various device and system embodiments may be included insome embodiments and not in others. Therefore, the foregoing descriptionis provided primarily for exemplary purposes and should not beinterpreted to limit the scope of the invention as it is set forth inthe claims.

The examples and illustrations included herein show, by way ofillustration and not of limitation, specific embodiments in which thesubject matter may be practiced. As mentioned, other embodiments may beutilized and derived there from, such that structural and logicalsubstitutions and changes may be made without departing from the scopeof this disclosure. Such embodiments of the inventive subject matter maybe referred to herein individually or collectively by the term“invention” merely for convenience and without intending to voluntarilylimit the scope of this application to any single invention or inventiveconcept, if more than one is, in fact, disclosed. Thus, althoughspecific embodiments have been illustrated and described herein, anyarrangement calculated to achieve the same purpose may be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the above description.

What is claimed is:
 1. An apparatus for delivering pulsed electricalenergy comprising: one or more high voltage switch drivers; one or morehigh voltage switches; and one or more multi-core pulse transformers,each multi-core pulse transformer comprising a first transformer coreand a second transformer core on opposite sides of a substrate, whereinthe first transformer core and the second transformer core each includeone or more cables forming primary and secondary windings, wherein theone or more high voltage switch drivers are coupled to the primarywindings such that each primary winding is electrically parallel toother primary windings, and the one or more high voltage switches arecoupled to the secondary windings such that each secondary winding iselectrically parallel to other secondary windings.
 2. The apparatus ofclaim 1, wherein each primary winding is between the one or more highvoltage switch drivers and the one or more high voltage switches.
 3. Theapparatus of claim 1, wherein each secondary winding is between the oneor more high voltage switch drivers and the one or more high voltageswitches.
 4. The apparatus of claim 1, wherein the apparatus isconfigured to keep each of the first transformer core and the secondtransformer core below saturation to reduce an inductance and increase aswitch drive current.
 5. The apparatus of claim 3, wherein the secondarywindings are coaxially arranged relative to the primary windings.
 6. Theapparatus of claim 1, wherein the apparatus is configured to provide ahigh voltage pulsed output comprising nanosecond pulses.
 7. Theapparatus of claim 1, wherein the one or more high voltage switches areMOSFETs and the one or more high voltage switch drivers are MOSFETdrivers.
 8. The apparatus of claim 1, wherein the first transformer coreis independent from the second transformer core.
 9. The apparatus ofclaim 1, wherein the first transformer core is on a first side of aprinted circuit board (PCB) to which the one or more high voltage switchdrivers and the one or more high voltage switches are attached.
 10. Theapparatus of claim 1, wherein the one or more cables forming the primaryand/or secondary windings of the first transformer core are woundbetween 1 and 5 times around the first transformer core.
 11. Theapparatus of claim 1, the apparatus is configured as a part of a pulsegenerator system.
 12. The apparatus of claim 11, wherein the pulsegenerator system comprises a pulse generator and a pulse delivery outputconfigured to deliver a high voltage pulsed output produced by the pulsegenerator.
 13. The apparatus of claim 12, wherein the pulse deliveryoutput comprises a plurality of electrodes.
 14. A method of generating apulsed output, the method comprising: emitting a driving pulse from ahigh voltage switch driver to a multi-core pulse transformer through aprimary winding of a first transformer core and a primary winding of asecond transformer core; and receiving the driving pulse at a highvoltage switch from a secondary winding of the first transformer coreand the second transformer core, wherein the first transformer core andthe second transformer core are arranged in parallel on opposite sidesof a substrate.
 15. The method of claim 14, wherein the pulsed output isin a nanosecond range.
 16. The method of claim 15, wherein the highvoltage switch is a MOSFET and the high voltage switch driver is aMOSFET driver, and wherein MOSFET, MOSFET driver and the firsttransformer core are on a first side of the substrate, and the secondtransformer core is on a second side of the substrate directly oppositefrom the first transformer core.
 17. The method of claim 14, furthercomprising emitting the driving pulse through a plurality of primarywindings that are arranged in parallel.
 18. The method of claim 14,wherein receiving comprises receiving the driving pulse at the highvoltage switch from the secondary winding that is arranged coaxiallyrelative the primary winding around the first transformer core and thesecond transformer core.
 19. The method of claim 14, the methodcomprises lowering circuit inductance to reduce driving point inductanceat high voltage switch driver outputs.
 20. The method of claim 14,wherein the multi-core pulse transformer comprises more than 2transformer cores.